1. Field of the Invention
This invention relates generally to slits used in optics. It further relates 40 optical systems that use precision slits that must be precisely aligned and adjusted. The present invention even further relates to slits for x-ray optics and optical systems in which temperature of the slit materials is important. It still further relates to ultra high vacuum systems. The present invention yet additionally relates to precision slits wherein the opposing edges of the slit must be precisely moved relative to a center line between the edges with each edge retaining its parallel orientation with respect to the other edge and/or the center line.
2. Description of Related Art
Slits have been used in optical instruments for more than 50 years. The precision with which slit dimensions must be determined are a function of the wavelength of the light or electromagnetic radiation that passes through the slit. The shorter the wavelength, the more precise the slit opening must be. In the current state of the art, the slit width is controlled by driving a wedge into, or retracting the wedge out of, one end of the slit opening.
In ultra high vacuum devices it is very difficult to achieve fine motion because cleanliness requirements prevent use of lubricants such as oil. Thus fine and precise motion of metal parts, such as a wedge, against other metal parts, such as the slit edges, is problematic. An additional problem with using a wedge to adjust the slit width is that the edges of the slit lose their parallel alignment because the wedge is driven between the edges from only one side. Further, the distance of each edge from the center of the Opening must remain equal in order to maintain slit alignment. This in turn requires that the wedge is exactly symmetrically shaped and is inserted and moved with its axis of symmetry exactly parallel to the slit edges; this is very difficult if not impossible to achieve in an ultrahigh vacuum environment. When wavelengths approach those of x-rays additional problems arise. The metal edges of the slit absorb energy from incident x-rays causing them to heat. The dimensions then change due to thermal expansion. Further, temperature gradients distort the slit opening during operation of the instrument.
In view of the above limitations and problems in use of the existing optical slits, it would be desirable to have an optical slit that could be finely adjusted in an ultrahigh vacuum environment. It would also be desirable to have a slit that reliably and easily maintained parallel alignment of the edges when it was adjusted in an ultrahigh vacuum environment. Further it would be desirable to have an optical slit that did not significantly expand and distort due to thermal gradients caused by absorption of the radiant energy in the optical beam.